This project investigates the sensory and memory underpinnings of language processing in individuals with Williams syndrome (WS) and Down's syndrome (DS). Both syndromes are genetically-based neurodevelopmental disorders characterized by an uneven profile of language strengths and weaknesses. In the presence of mild-to-moderate mental retardation, individuals with WS show relative strengths in phonology, verbal short-term memory, and expressive vocabulary. In contrast, individuals with DS show relatively weak phonological abilities, poor verbal short-term memory, and diminished expressive vocabulary. In spite of minimal empirical support, current theories about language function in WS are frequently grounded upon an assumption of relative strengths in auditory processing. [unreadable] [unreadable] First, behavioral auditory measurements are examined including air conduction, tympanometry, otoacoustic emissions, simultaneous and backward masking. These measures are then compared with both (a) physiological responses indexing early auditory memory and (b) phonological analyses indexing early language processing. The inverse pattern of strengths and weaknesses in these two clinical populations provides an opportunity to: (1) empirically examine auditory sensitivity in individuals with WS, (2) empirically test the hypothesis that short-term auditory processing is particularly robust in individuals with WS, and (3) test a current hypothesis that there is a strong correlation between auditory processing, auditory memory, and phonological processing in two groups with confirmed genetic disorders. Important clinical applications are to investigate the possibility of higher-than-expected instances of hearing loss in WS and to identify auditory interactions with language function. [unreadable] [unreadable] [unreadable]